The present invention relates generally to new and useful methods and devices for packaging food products, and more specifically, to improved stuffing horns with presizing devices for tubular food casings.
In the manufacture of sausage products, a tubular food casing, such as nonedible cellulose is loaded onto the stuffing horn of a filling machine and stuffed with an emulsion, usually comprised of comminuted meat together with fillers, seasoning, spices, etc. In the case of small sausage products, like frankfurters, the filled casings are twisted, tied or clipped into suitable links at predetermined intervals and further processed. For larger sausage products, like bolognas, salamis, and the like, the meat emulsion is introduced into larger, heavier walled fibrous type casings and formed into chubs or lengthy individual sausage sticks.
In preparing large diameter sausage products, like bologna, an important consideration is the maintenance of accurate size control over the entire length of the sausage stick. It is particularly important that the diameter of large sausage products be carefully controlled so that meat packers are able to cut the sausage into slices of predetermined thickness and diameter for prepackaging. The objective is to have a given number of slices weigh precisely a predetermined amount for each package.
In stuffing larger sausage products, however, there is some tendency for diameter variations to occur which may be due to varying stretch properties of casings and meat emulsion charging pressures. There may be less variation in product diameter with sausage stuffed in fibrous casings than nonreinforced type casings. Nevertheless, meat processors are constantly striving to improve operations which affect finished package yields. Constant control during stuffing of green stick diameter assures more uniform slice weight and minimizes package over and underweight variations.
To facilitate stuffing and also obtain greater dimensional uniformity in filling larger food casings, presizing devices have been used for diametrical stretching. This is achieved by longitudinally passing tubular casing prior to filling, in most instances over a stationary type sizing device which operates to stretch the casing to the stuffed diameter recommended by the manufacturer. In addition to the stretching action of the presizing device, casing moving over some devices generates friction. This creates drag or holdback forces on the casing increasing the diameter of the filled casing and vice versa depending on the extent of the forces being exerted.
To improve stuffing efficiency, U.S. Pat. No. 4,007,761 (Beckman) discloses a self-sustaining tubular casing article with a presizing ring prepackaged in the deshirred end of a shirred strand. The objective is to facilitate the filling process by engaging both a new shirred strand of casing together with a presizing ring to the stuffing horn in a single operation. Others, such as U.S. Pat. Nos. 4,512,059; 4,528,719 and 4,535,508 have sought to improve on the Beckman concept by means of expandable sizing rings of the type which can be readily attached to stuffing machines by also prepackaging in the deshirred ends of strands. After engaging the strand with the stuffing horn, the sizing ring can be expanded from an unexpanded state to a casing stretching size by manipulation of the ring on the horn directly through the casing wall. This facilitates both assembly and use of the casing/sizing ring article, since it can be more easily implanted into the casing by the casing manufacturer in a collapsed state, and latter expanded to a casing stretching size by meat processors.
For the most part, presizing rings have relied on attachments to the filling horn. Such devices are frequently based on costly, noneconomic designs, especially in view of the fact that many are disposable or "throw-away" after use articles. For example, the presizing discs of U.S. Pat. No. 4,535,508 comprise a multiplicity of radial arms each having a nonmovable rod passing through a hollow guide. The outer end of each rod has a flattened casing contact which engages with the interior wall of the casing on the horn when inner rod lifters are compressed when mounting to the stuffing horn. U.S. Pat. No. 4,512,059 discloses a device having a plurality of petal-like sizing members arranged around a central hub. Expansion of the petals to size the casing is dependent on each making frictional contact with the casing during stuffing instead of being automatically expanded upon engagement with the stuffing horn like U.S. Pat. No. 4,535,508. U.S. Pat. No. 4,528,719 discloses a two-piece sizing ring comprising a casing engaging first element and a rigid disc second element. In order to expand the first element for engaging with the casing, the second inner disc must be compressed to engage with the first element. Although such sizing devices are useful, production costs would detract from generally wide acceptance.
Accordingly, there is need for a more economic means for presizing casing during the filling process which can be used repeatedly, and which is an integral component of the filling machine, while allowing installation of unfilled casing without interference.